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Full text of "Handbook Of Chemical Engineering - I"

140                              CHEMICAL ENGINEERING
CAPACITY1
(35)  Number of gallons of water discharged in 24 hr., as measured.............gal.
(a) Number of gallons of water discharged  in 24 hr.,  calculated from
plunger displacement, corrected................................gal.
(&) Gallons of water discharged per min., as measured..................gal.
(c) Gallons of water discharged per minute, calculated from plunger displacement, corrected..........................................gal.
ECONOMY RESULTS
(36)  Heat units consumed per indicated horsepower-hour....................B.t.u.
(37)  Heat units consumed per water horsepower-hour.......................B.t.u.
(a) Dry steam consumed per indicated horsepower-hour.................Ib.
(6) Dry steam consumed per water horsepower-hour....................Ib.
EFFICIENCY RESULTS
(38)  Thermal efficiency referred to indicated horsepower [(2546.5 ^ Item 36) X 100].
........................................................per cent
(a) Thermal efficiency referred to water horsepower [(2,546.5 4- Item 37)
X 100]..................................................per cent
(6) Mechanical efficiency [(100 X Item 32)/Item 31]................per cent
(c) Pump efficiency [(100 X Item 32)/Item 31a]....................per cent
DUTY
(39)  Duty per 1,000,000 heat units.......................................ft.-lb.
WORK DONE PER HEAT UNIT
(40)  Foot-pound of work per B.t.u. (1,980,000 -f- Item 37)...................ft.-lb.
SAMPLE DIAGRAMS
(41)  Sample indicator diagrams from each steam and pump cylinder...............
NOTE.—The items relating to indicator diagrams and indicated horsepower are to
be used only in the case of reciprocating machines.    The indicated horsepower on which the economy results are based is that of the main engine, given by Item 31.
Operating Direct-acting Pumps.—Small pumps are provided with a pet cock on the discharge chamber for blowing out the air. On larger pumps a starting valve, or waste valve, should be placed on the discharge pipe inside of the gate and check valves. Prime and start the pump with the waste valve open to work the air out of the pump chambers. If there is a check valve, this will open automatically when the right speed is reached, but if there is only a gate valve, a gage should be placed at some point inside of the gate valve, which will indicate the proper time to open the gate valve, viz., when the pressures on both sides are balanced. Both sides of a duplex pump should be packed alike, or one side will travel at a higher velocity than the other.
Before opening the throttle valve blow out the steam pipe. If cylinders are jacketed admit steam to the jackets some time before starting. If air pump is independent start same and get up a vacuum before starting the main engine. After stopping open all blow off s and drain valves. If it is to be idle for some time open the cock of the oil cup, so as to let the oil flow into the steam chest, then let the pump make a few strokes to distribute the oil well over the inside of the steam end. When a pump is to be drowned, flood cylinders with oil and shut off steam from the surface.
1 Capacity in gal. per 24 hr. = 74.8ASNt corrected for leakage; in direct-connected engines, 8 = average length of stroke.